During the packing of pourable, but somewhat bulky, products in foil tubular bags, the products have a tendency to bridge across the bag thereby clogging the bag. This can occur frequently as the bags are being filled. As a result, care has to be taken as the bags are being sealed to ensure that pieces of the bulk goods do not remain hanging in the region of the tubular bag being sealed. Bags are typically seated at a seam between a pair of sealer jaws or tools. It is important to ensure that crumbly products and pieces do not remain hanging in the area of the sealed seam due to uncontrolled fall-in. Potato chips because of their low specific weight are a typical example of a troublesome product.
Even with very precise metering, due to the varying character of the product, pieces of the product filling the bag can float or remain hanging in the area of the seal at the moment that the sealing tools seal or close. If these pieces of product or bulk goods are sealed in the region of the seam, then the bag may remain open or seal in an unattractive fashion so as to be unsaleable.
In a typical bag producing device, the welding or sealing tools are mounted on pairs on rotating axles. The axles are positioned on both sides of the tubular foil and turn the sealing tools synchronously in such a way and at a rotational speed such that the opposing sealing tools meet each other after they pass the length of a bag. After meeting on opposing sides of the foil, a pair of tools travel straight together a short distance with the foil. The bag is subsequently sealed with a second pair of tools attached to the opposite side of the axles (i.e. the tools are offset 180 degrees).
Conventional seal tools typically have an associated closing bar that presses the tubular foil together. The seal tools also may include a stripper mounted on the turning axles, ensuring that the foil is pressed together and stripped before the sealing tools meet each other. The foil is thus prepared for the sealing process and at the same time, fall-in of the bulk goods into the area of the seal is prevented. The stripper removes the residue of the bulk goods on the inside of the tubular foil from the region of the seam.
European Patent Application 666215 A1 discloses a bag closing device in which the closing bars and the bar-shaped strippers are mounted on a support plate next to the support for the sealing tools and at a right angle to the foil passing through. The closing bars and the bar-shaped stripper swivel on their supports and are spring-loaded so that they can press the foil together as well as stripping the residue of the bulk goods from the area of the seal with a wiping motion.
To protect the welded tubular bags from the hot sealing tools, EPA 666215 A1 discloses wing-like shields attached to the bars and positioned between the just-sealed bag and the sealing tools. The closing bars serve as strippers, and are moved by the driveshafts. In order to ensure that the sealing tools press the tubular foil together and heat it for the time necessary for sealing, the tools are attached so that they are axially movable and are loaded with compression springs. The circular movement of the sealing tools is modified into a straight line during the sealing segment. One full rotation of the axles that support the sealing tools produces two sealing processes.
The disclosed device has several disadvantages. The attachment and bearing of the necessary components makes installation difficult, requires space, and makes the device sluggish in its movements, thereby also reducing the clock rate of the packing device. Furthermore, because the rotating movement cycles and movement axes can only be positioned opposite to one another in a limited way, the effective zones of the closing bars and the strippers are restricted to a limited area.
The sealing device disclosed in U.S. Pat. No. 4,663,917 operates in a similar manner. German Patent Application No. DE 400 50 078 discloses a sealing device in which the closing bars are attached to the sealing heads directly using springs. The foil on both sides of the sealing tools or jaws is pressed together by the spring-loaded closing bars. A stripping motion is not provided in this design.
The device disclosed in German Patent Application No. DE 24 01 800 does use a stripper, but the stripper only functions as the closing bars described above. A direct connection and movement of this component with the sealing tool in the sense of a stripping movement is not given.
Thus, there remains a need for a bag producing device that includes closing bars and strippers positioned directly on the sealing tool or the tool mount, that provides for movement of these elements so that a secure operating cycle is produced at a high clock frequency.